Posted
by
samzenpus
on Sunday January 22, 2012 @10:56AM
from the raise-shields dept.

arisvega writes in with a story about an international organization that is trying to come up with options to save the planet from a large asteroid or comet collision. "NEOShield is a new international project that will assess the threat posed by Near Earth Objects (NEO) and look at the best possible solutions for dealing with a big asteroid or comet on a collision (PDF) path with our planet. The effort is being led from the German space agency's (DLR) Institute of Planetary Research in Berlin, and had its kick-off meeting this week. It will draw on expertise from across Europe, Russia and the US. It's a major EU-funded initiative that will pull together all the latest science, initiate a fair few laboratory experiments and new modelling work, and then try to come to some definitive positions. Industrial partners, which include the German, British and French divisions of the big Astrium space company, will consider the engineering architecture required to deflect one of these bodies out of our path."

They are looking at the issue from the wrong direction. We should not work for ways to destroy or deflect an asteroid. There are many other things that can cause catastrophic loss of life on this planet, from 'mega-volcanoes', nuclear war, epidemic diseases, and yes even -gasp- climate change.

Instead of moving the danger of our path, we should be moving ourselves off the path of danger. We need an off site backup for humanity at least, if not as much of the biosphere as we could manage. Eventually, something WILL destroy 99.9% of life on Earth. It has happened before and will again, whether 10 years or 10,000 years from now.

Yep. And, early detection is most important. Waiting til the damned huge ass rock is a month away ensures that our best efforts will be worth shit. If we can get a team on the rock a year before impact, even a tiny deflection in it's course will work to avert disaster.

Of course, a nuke isn't necessary, if you get on the rock early enough. A few tons of thrust from a chemical rocket would be good enough. Or, a chemical bomb dropped down the well that you've drilled. Nukes are sexy, but not essential.

Any other location would be just as volnurable (or even more) to an asteroid as Earth is. So why not do both? Expand beyond Earth AND develop ways to stop asteroids? If one hits Earth it will be many thousands of years (even if we presume that it survives and absolutely everything goes well) before a colony would be capable of developing anything that could defend it from subsequent strikes.

This is reality, where detonating an asteroid with a nuclear bomb just turns it into millions of pounds of rocks and dust that will hit the earth anyway. As it is the dust that will kill the whole planet's ecosystem, a nuke is the opposite of the right idea.

That's a great mix of science and bullshit you've got going on.

Yes, you're correct that a nuke would turn a solid core object into a shotgun blast of rubble.No, you're not correct that the danger is from the dust flying through space. The dust you're thinking of is what gets kicked up into the atmosphere following an actual impact.

If you could reduce the solid object into rubble, yes it will still hit the atmosphere. But any of the individual pieces which are small enough will simply burn up before impact, and won't have any significant impact on the atmosphere or ecosystem.

As a practical experiment to demonstrate the principle, do this. Get a solid block of ice from your local grocery store. Set it on your kitchen counter. Get a second one, and use a hammer to smash it into pea-sized chunks. Leave this on another counter. Pay attention to which melts first- the solid block or the pile of rubble.... hint: it will be the rubble.

Having said all that, launching a nuke isn't really much of an option in the first place. Most of the destructive power from a nuke is actually a result of the shockwave caused when you detonate one within a pressurized environment, in our case the atmosphere. In space, there's no pressure so all you get is energy release in the form of radiation... which means other than irradiating it and possibly melting part of it due to the heat generated when the radiation hits the object, a nuke won't really do much at all. You would have to pull a Hollywood stunt and actually Bruce Willis into the object for an explosion to have any significant effect, and even then it wouldn't reduce it to rubble but more likely just split it into a few very large chunks.And if it was not a single solid core object, but a collection of rubble or just a very low density, then we'd really be shit out of luck. Of course, it wouldn't have nearly as much of a chance to actually impact the planet, and more would burn up in the atmosphere.

In any event, the biggest issue with deflecting an asteroid is that they don't usually just float along. They spin and tumble. So attaching a thruster or a bomb would probably not be effective even ignoring all the other issues.